John "Marmaduke" Dawson, a singer-songwriter who co-founded the psychedelic country-rock band the New Riders of the Purple Sage with the Grateful Dead's Jerry Garcia, died Tuesday in Mexico after a bout with stomach cancer, the band announced. He was 64.

Mr. Dawson, who retired to Mexico in the 1990s, formed the New Riders in 1969 with Garcia, who needed a band outside of the Grateful Dead to practice his nascent pedal steel guitar playing.

Fronted by Mr. Dawson, the lead singer, the New Riders released eight albums on Columbia Records from 1971 to 1976, including "The Adventures of Panama Red," a gold record that featured Peter Rowan's pot paean "Panama Red."

As a songwriter, Mr. Dawson co-wrote the Grateful Dead classic "Friend of the Devil," as well as "Glendale Train," "Garden of Eden" and "Last Lonely Eagle" for the New Riders.

The band became a successful touring act, and in 1974 played for 50,000 fans in New York's Central Park. They shared an office on Second Street in San Rafael with another Marin band, Commander Cody and the Lost Planet Airmen.

Saying he was weary of life on the road, Mr. Dawson retired in the late '90s. In 2001, he rejoined his former bandmates for a one-off concert at a California party, but he chose not to participate in a version of the band that regrouped in 2006 and remains active today. But he gave his blessing.

"John Dawson had a great knack for writing classic American songs," said Marin resident Rob Bleetstein, the New Riders' archivist and Web master. "A song like 'Glendale Train' could be looked at as a traditional American folk song.

"In terms of American music, the New Riders were the quintessential psychedelic country band," Bleetstein added. "In 1969, there wasn't anyone doing what they were doing. With Garcia's sound on pedal steel and Dawson's great songs and imagery, they really had something special."